How do you brink them down. I am stuck between 40 and 50ppm. I do water changes and add chemicals... this tank does not have a skimmer on it and has some live rock,
Using 2lbs of rock per gallon
Large skimmer
Doing 50% water change will bring it down by half, then another 50% change the next day will bring that number down by half again.
Carbon Dosing
Large Sump with macro algae
Algae Turf Scrubber
There are a fewe things you can do.
What type of filtration are you using? Are you using rodi water? And what chemicals are you using? If you are housing corals a skimmer will help. You might also want to cut down on feeding .Excess nutrients will cause nitrates to spike without a proper filter system.